@jackslate Search up "In Ear Monitors detached" on google images. IEMs are modular that way for various reasons, most probably because the wire itself would be expensive and that if one "driver" fails you can replace one instead of getting rid of the whole thing.
Musicians and sound engineers use these kinds of head phones a lot for monitoring while performing concerts, but audiophiles enjoy them too because of the clarity of the sound (it has a "flat" sound) before any kind of equalization or bass boost is applied.